as far as i remember from older versions, only with the highest tier version you can fully utilize hardware synths (some artist wrote on forum). But i suggest you to check the link i gave and also demo.

Probably. Do you care about midi effects because you get zero. You'll get more audio, group and midi tracks than I'd ever use. I think for people that are not doing huge productions the higher versions are mainly to be considered if there is something you really want. I bought Pro because I wanted audio quantize. You really have to look at this:

Unfortunately, it's not even possible with dirty workarounds... the only thing you can do is using fake sidechaining like LFO Tool or VolumeShaper. Cubase from Artist on has sidechaining though, even though it's limited to VST3's. Which might be a bummer as well, if your favorite compressor is VST2 only.

...I’m hoping for a stable DAW to run plugins and control external hardware synths...

So why would you choose Cubase?

Ever since last fall I’ve been having ongoing problems getting Bitwig to send MIDI out. Not sure why. It’s connecting to all my USB devices and I can use them all as controllers, but they can’t be controlled. For instance, I can use my Pro 2 as a controller for any software instrument, but if I try to get it to control my Dominion 1, or try to use my Novation Remote to control it, it does not work. It’s an on an off problem that’s been happening for a while and I’m tired of fighting it, so I’m considering moving on to another DAW. I’ve got very little time, these days, to play music, and this weekend I grabbed a couple of hours to play and instead I spent it dealing this this issue.

Unfortunately, it's not even possible with dirty workarounds... the only thing you can do is using fake sidechaining like LFO Tool or VolumeShaper. Cubase from Artist on has sidechaining though, even though it's limited to VST3's. Which might be a bummer as well, if your favorite compressor is VST2 only.